Method of protecting systems for transporting media corrosive to metal



Jan. 25, 1949. KAHLER 2,460,259

METHOD OF PROTECTING SYSTEMS FOR THANSPORTING MEDIA CORROSIVE TO METAL Filed Jan. 22, 1946 METAL CORROSIVE LIQUID MEDIUM METAL METAL CORROSIVE LIQUID MEDIUM U NTREATED METAL INVENTOR fiar'ryllewals fi'afiler Patented Jan. 25,1949 2,460,259

METHOD OF PROTECTING SYSTEMS FOR gilATNAiPoRTlNG MEDIA CORROSIVE TO Harry Lewis Kahler, riaasterville, Pa., assignmto W. H. and L. D. Beta-Philadelphia, Pa., a

Application January 22, 1946, Serial No. 642,769

'7 Claims. (01. 117-97) My invention relates to a method of protecting treated metal specimen indicating the nonthe surfaces of pipe lines and apparatus in conwetting characteristics which the treatment has tact with transported media corrosive to metal. imparted to the metal. The corrosive liquid The corrosive action may be caused by carbon medium has assumed drop form because of the.

dioxide, oxygen, ammonia, hydrogen suifiide, 5 non-wetting film on the metal. Fig. 2 is a similar sulfur dioxide or other substances, in a gaseous, view of an untreated metal specimen, but in this vaporous or liquid state or media, or by the media case the liquid medium spreads over the metal itself, or both. surface. Whereas in Fig. 2 the corrosive liquid Where an attempt has hitherto been made to medium has intimate contact with the metal and reduce the corrosive action, such method emcan thereby corrode it, the metal in Fig. 1 is proployed substances which combined chemically tected by the non-wetting film which prevents the with the corrosive elements in the media to remediiun from intimate contact with the metal duce the corrosive characteristics. Where 'exand thereby prevents corrosion of the metal.

pensive substances have been so employed, the I have discovered that numerous substances cost has been high, and certain by-products may 1 may be added in small quantities to media such be formed which present problems of disposition. as corrosive gases, vapors and liquids, without I have discovered that the most convenient affecting the media in any material manner, to method of protecting the metal surfaces of the form a thin, substantially monomolecular film on system is to provide a film on the contacting the contacting surfaces of the pipe line and assosurfaces of the transporting system which will elated quipm nt P v in h media f om prevent the transported media from touching the corrosivel attacking such surfaces. Among the surfaces, and I, therefore, have as my primary substances that form this non-wetting film are: object the formation of such a film.

The efllciency of turbines and other moving GROUP I' THE Egg WEIGHT apparatus in the systems may be seriously affected by the deposition of a thick film, and my further (a) Primary amines or their salts having object is to provide a substantially mono molecstraight carbon chains from C10 to Cm. uiar film which will not materially change the surface characteristics of the metal. Examples In order that such a film will maintain its coroctaaecylamine rosion-prevention function, I have determined Hexadecyhmme' (3183331531.;2 that such a film should be of the type which Tetmdecylamme,CMHZQNH, would prevent the media from Wetting the cOn- I salt: octadecylamine hydro hloride tacting surfaces of the transporting system.

This then is a further object of my invention. C1cH3'zNHaHC1 The method of applying the film is important.

- For example, if the system had to be periodically g? i i m f z having emptied of the media, while the film is being g car on c mm mm 0 deposited, such a procedure would be both costly Examples and arduous. Therefore, still another object is 40 to provide a method whereby the film can be Dldmiecylamme deposited while the system is being used. 0113::

A corollary to such an object would be to pro- NH vide a substance which could be added to the media, and in such small quantities that the 4 media would not be materially affected. This Dioctadecylamme would have the added advantage of reducing the 01.1131 cost. NH

I accomplish these and other objectives, and obtain my new results as will be apparent from a consideration of the substances and methods of lt: ido e yl min hy ro lfate employing them, disclosed in the following specification, particularly pointed out in the attached NH H 0 claims and illustrated in the accompanying drawing in which: Fla. 1 is an enlarged side view of a M Examples anccl1i passing the vaporized substance into the me a.

In the following static test, low carbon steel specimens having an area of six square inches Tridodecylamine, (CuHns) aN 5 were immersed in a. corrosive media consisting oi Trihexadecylamine, (CmHaahN carbon dioxide, oxygen and water, at a tempera- Trioctadeoylamine, (ciaHa'ziaN ture of 180 F.; 200 P. P. M. of film forming Salt: d yl m hy l substance were introduced into the media; and

(CnHamN-HCzI-Iaw the specimens were subjected to a one-day ex- (d) Unsaturated members of each or a, b 10 pogure, and

Examples 1 Q-octadecenylamine, Loss or Steel In Milligrams at 7CH3(CH2) 1CH=CH(CH2) 1CH2NH2 Different PH V ues 9-12-octadecadienylamine, l5 Material-i (e) glgggghhCH=0HCH=CH-CH(CH:MNH: L0 M 4 6 6 7 8 10 Example Loss without treatment (Ava) 862 210 00 31 as 36 as 32 CH3 :0 Octadecylamine acetate-.- 369 100 45 11 1 7 25 sate-mazes; a a a t a 2 a CHwHMNH Dodecylamine acetate 150 25 s 11 1o 27 om entre "55' *2 2 s a t8 1) Derivatives 2" ifgggfiei ytaaataa aa: .If. 32 2? 3 3 i3 53 and mixtures of a, b, c, d and aoggizitzghexndecyl, 50%9-octadecenyi,30%9-12octadecadicnylamine GROUP II THE LONG CHAIN FATTY ACID PARTIAL 25% octadecyl, o hexadecyl, octadecenyl amino acetates.

ESTERS OF HEXITOL RIDES 30 e Amine acetate res dues of fatty acids oi the cocoanut oil series.

Examples Table 1 shows the efiectiveness of many of the substances in reducing the corrosivity of steel. sorbltan monolaurate The pure amines were Just as efiective as the sorbitan monosteamte 85 amine salts. The table shows further that dit- GROUP III.-AMINE Oxmes CONTAINING STRAIGHT ferent members of these groups work at diflerent CARBON CHAINS FROM C1 'ro Cm pH values, giving more flexibility to thistype of Examples treatmentin that a choice can be exercised when the pH of the medium demands it. Thus, for cetyl dlmetyl anfline oxide 0 example, octadecylamine could be selected for pH Qwctadecenyl dlmethyl amine xide range 1-7, and dioctadecylamine for pH 6-7 and Generally the following results were observed didodeeylamine f DE I Table 1, the se from the various experiments: of these filming substances required moretreat- (a) Film found is substantially monomolecular. ment as the D Went below DH range (12) Can select a film iorming substance which 45 13.5 the use of concentrations of not more than Functions best at a particular pH of the media. 5% is recommended. Above pH 3.5,- r 0 11- (c) Less film forming substance required as pH centrations 01 not more than 100 P. P. M. were ncreases proved to be satisfactory.

(d) Even 1 P. P. M. of film forming substance In the following test, simil r steel Specimens rave satisfactory results. were immersed in a corrosive medium consisting (e) Film forming substance required for media of water, carbon dioxide, and oxygen, constantly iaving pH from 3.5 to 10 did not materially flow g at 5 temperature of 6 Various :hange the composition of the media. amounts of the substance were introduced in (j) Film provides protection .over wide range the media moving continuously past the specimen f temperatures. I for an exposure of two days.

TABLE 2 L is: 1, Analysis of Tmnment I 0532a Go Medium P P M Conductiv- Per Cent Test ity Micro- Saving oi speck Speci mhos Steel Typo P. P. M. maul mmz pH C01 0:

I 94 as so 66 0.01 n t a t' iih'fine acetate... 0 154 a 1 5.1 0 20 91. 8tfi itfitifi at 13 2'3 12 i3 3% O tad glamine acetate:: 1 '31 as 411 "336' -oI2 2o 01 I No treatment.

(g) Steel, brass and other metals protected by 70 Table 2 shows that even 1 P. P. M. gave satisfactory results for a moderately acidulated 21%: 1 3 313321 protection even if metal medium in the presence of oxygen. Table 2 The film forming substance may be added also shows that the added treament did not materially change the composition of the medium.

:ctly to the media or by vaporizing the substance In the following tests, the conditions were substantially identical to those given in Table 1.

TABLE 3 Temp., Film Test Temperature Formation Octudecylamine 70 Good.

. Hexadecylnmine 70 Do. Tetradecylamine 70 Do. Dodecylemine 70 Do. Dioctadecylamine.. 70 Do. Didodecylamine 70 Do, Q-Octadccenylnmine 70 Do. 9-12 Octadecadienylamlne. 70 Do. Sorbitan monolaurate 70 Fair. Sorbitan monostearatc 70 Do.

Cetyldimethylnmine oxide." 70 Do.

9-Oetadecenyldlmethylamine 70 Do.

oxide. ctadecylamino l80 Good Hexadecylaruine 180 o Dodecylamine 180 Fair Octadecylamine Hexadecylamine 180 Good Octadecenylamine 17 Sorbitan monolaurate I80 Fair. 18. Octadecylamine 205 Good.

These filming materials provide protection against the corrosivity of media over a wide range of temperature. Table 3 illustrates this point, where good films were obtained over a range of 70 to 205 F.

In the following tests, similar steel specimens were immersed in a corrosive media consisting of water, carbon dioxide and oxygen, constantly flowing at a temperature of 205 F.

1No treatment was supplied but corrosion specimens employed had illms from 2 days treatment as in Test 2.

1 Average.

Table 4 shows the test on the residual film left after treatment was stopped, and it indicates that the film deposited from 1 P. P. M. was about as protective at the end of one day without treatment as it was while treatment was continuously being supplied. As time was extended beyond one day, the film became less protective. Thus, for best protection, it is recommended that the treatment be fed continuously to keep the metal surfaces saturated to provide the most impervious and continuous film.

While most of the work was done with steel surfaces, suificlent results were obtained with red brass, yellow brass and other metals, to prove that metals generally are also protected by this non-wetting film. It is also true of corroded steel specimens which were tested for film formation. This film formation which is laid on the corrosion deposits is very important industrially as most of the metals in use are in a corroded condition and therefore do not have to be replaced by new metal to make this new type of treatment applicable.

The solubility of the film amines increases with increased acidity of the media, and generally the film is more eifective with increased acidity, ex-

cept where the straight carbon chain reaches the lower molecular weight range.

By substantially mono-molecular film, I mean a film that approaches mono-molecular dimensions.

I have thus described my invention, but I desire it understood that it is not confined to the particular forms or uses shown and described, the same being merely illustrative, and that the invention may be carried out in other ways without departing from the spirit of my invention, and, therefore, I claim broadly the right to employ all equivalent instrumentalities coming within the scopeof the appended claims, and by means of which, objects of my invention are attained and new results accomplished, as it is obvious that the particular instrumentalities herein shown and described are only some of the many that can be employed to attain these objects and accomplish these results.-

I claim:

l. The method of protecting the metal contacting surfaces in a continuously flowing system for transporting aqueous media having corrosive qualities which comprises the step of adding to the transporting media an aliphatic compound taken from a group consisting of the high molecular weight amines, amine salts, and amine oxides, having straight carbon chains in which the straight carbon chains contain from 10 to 18 carbon atoms in concentrations of not more than 100 P. P. M., the media having a pH of not more than 8, the amount of compound being sumcient to form on the surfaces of the system a uniform film having the characteristics of being mono-molecular, of being non-wetting and capable of blocking the corrosive action of the media and conveying the media suiiiciently to allow the film to form.

2. The method of claim 1, wherein the compound added has the property of blocking the corrosive action or the media. within a particular pH range.

3. The method of claim 1, wherein the system pound added is dioctadecylamine.

HARR Y LEWIS KAHLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

